Indium oxide resistor inks

Abstract

Improved medium and high value resistor inks are disclosed. The subject inks comprise indium oxide, a barium calcium borosilicate glass frit, a suitable organic vehicle and a temperature coefficient of resistance modifier selected from the group consisting of ferric oxide and vanadium oxide.

We claim: 
     
       1. A circuit board having on a portion of the surface thereof a coating of an improved resistor ink comprising: (a) from about 25 to about 80 percent by weight of indium oxide;   (b) from about 5 to about 60 percent by weight of a barium calcium borosilicate glass frit;   (c) from about 10 to about 35 percent by weight of a suitable organic vehicle; and   (d) from about 0.1 to about 10 percent by weight of a temperature coefficient of resistance modifier selected from the group consisting of vanadium oxide and ferric oxide.   
     
     
       2. A circuit board in accordance with claim 1, wherein said board is porcelain-coated metal. 
     
     
       3. A circuit board in accordance with claim 2, wherein said metal is steel. 
     
     
       4. An electronic assembly comprising a circuit board having a circuit thereon, said circuit containing a resistor film formed by applying and firing a resistor ink comprising: (a) from about 25 to about 80 percent by weight of indium oxide;   (b) from about 5 to about 60 percent by weight of a barium calcium borosilicate glass frit;   (c) from about 10 to about 35 percent by weight of a suitable organic vehicle; and   (d) from about 0.1 to about 10 percent by weight of a temperature coefficient of resistance modifier selected from the group consisting of vanadium oxide and ferric oxide.   
     
     
       5. An electronic assembly in accordance with claim 4, wherein said modifier is present in said ink in an amount of from about 1 to about 5 percent by weight. 
     
     
       6. An electronic assembly in accordance with claim 4, wherein said resistor film has a resistance value between about 50,000 and 1 million ohms per square and said modifier is vanadium oxide. 
     
     
       7. An electronic assembly in accordance with claim 4, wherein said resistor film has a resistance value between about 500 and 5,000 ohms per square and said modifier is ferric oxide. 
     
     
       8. An electronic assembly in accordance with claim 4, wherein said circuit board is porcelain-coated metal. 
     
     
       9. An electronic assembly in accordance with claim 8, wherein said metal is steel. 
     
     
       10. In a resistor ink suitable for forming a resistor film on a circuit board comprising: (a) from about 25 to about 80 percent by weight of indium oxide;   (b) from about 5 to about 60 percent by weight of a barium calcium borosilicate glass frit; and   (c) from about 10 to about 35 percent by weight of a suitable organic vehicle;   the improvement wherein said ink contains from about 0.1 to about 10 percent by weight of a temperature coefficient of resistance modifier selected from the group consisting of vanadium oxide and ferric oxide.   
     
     
       11. An improved resistor ink in accordance with claim 10, wherein said ink comprises from about 30 to about 45 percent by weight of indium oxide, from about 30 to about 45 percent by weight of said glass frit, from about 20 to about 30 percent by weight of said vehicle and from about 1 to about 5 percent by weight of said modifier. 
     
     
       12. An improved resistor ink in accordance with claim 10, wherein said glass frit consists of: from about 40 to about 55 percent by weight of barium oxide; from about 10 to about 15 percent by weight of calcium oxide, from about 14 to about 25 percent by weight of boron trioxide; and from about 13 to about 23 percent by weight of silicon dioxide. 
     
     
       13. An improved resistor ink in accordance with claim 12, wherein said glass frit consists of about 52 percent by weight of barium oxide, about 12 percent by weight of calcium oxide, about 19 percent by weight of boron trioxide, and about 17 percent by weight of silicon dioxide. 
     
     
       14. An improved resistor ink in accordance with claim 10, wherein said modifier is added to lower the temperature coefficient of resistance and said modifier is ferric oxide. 
     
     
       15. An improved resistor ink in accordance with claim 14, wherein the resistance value of a film formed therefrom is between about 500 and 5,000 ohms per square. 
     
     
       16. An improved resistor ink in accordance with claim 10, wherein said modifier is added to raise the temperature coefficient of resistance, and said modifier is vanadium oxide. 
     
     
       17. An improved resistor ink in accordance with claim 16, wherein the resistance value of a film formed therefrom is between about 50,000 and 1 million ohms per square. 
     
     
       18. An improved resistor ink in accordance with claim 16, wherein said vanadium oxide is vanadium trioxide. 
     
     
       19. An improved resistor ink in accordance with claim 16, wherein said vanadium oxide is vanadium pentoxide.